Alex, this is a simple decoupling exercise. The test port loads your signal with a relatively high impedance, while the scope port sees a low impedance, and smaller signal, sic resistor divider, large resistor to the test signal in series with a small resistor across the test port. The attenuation ratio sets the relative decoupling. Regards, Steve. At 10:00 AM 6/11/01 -0700, you wrote: >I'm looking for some techniques for probing differential signals 1 Gig and >above. I could use a differential probe but the one I have has no easy way >to connect to the board other than physically holding it which is not >acceptable. On the other hand I could use 50 Ohm coax with a SMA connection >except then the scope circuit becomes part of the PCB circuit. In some of >the papers at teradyne.com, they say they use an SMA connection in >conjunction with resistors to provide some isolation. Anyone have any >suggestions or know what circuit they are using to provide isolation? > > >------------------------------------------------------------------ >To unsubscribe from si-list: >si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field >For help: >si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field > >List archives are viewable at: //www.freelists.org/archives/si-list >Old list archives are viewable at: http://www.qsl.net/wb6tpu > ------------------------------------------------------------------ To unsubscribe from si-list: si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field For help: si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field List archives are viewable at: //www.freelists.org/archives/si-list Old list archives are viewable at: http://www.qsl.net/wb6tpu